Of very much so!! Hell, just the way the car is strapped to the rollers will change. The pressure will change the numbers as well. Try steady stating with a wheel that is not laying perfect in the rollers. The TQ jumps everywhere. All these factors count in a very big way. People take to much for granted in these test.

I also agree, in the end...WHO CARES. Run what ya brung and the end all is what it does in the car not on a stand.

Old hot rod trick was to take Bias Ply tires and pump them up to the point the sidewall could never move.

 

So comparing Horsepower of different cars on different dynos is somewhat pointless !!!!
I am sure dynos may be useful in some types to tuning but I know some guys who
(Todd @ Protomotive) measures horsepower on an engine dyno (you cannot argue
with his horsepower figures!!) and then tunes the car on the actual roadway where
real life things are happening like: air flowing over the car and into the various intakes
and speeds that are directly related to the car and engine speed, etc.!
We are now learning (hopefully) that a 600 hp stage 4, and a RUF 590 will
not perform (not even close), even though the stated horsepower is the same.

 

May be useful? The two most useful tools are steady state on a dyno then street. Engine dynos are great for initial development, but almost always will run too rich and need to be moderately retuned in the chassis. You can not shorten the process nor check the loads on the street properly.

Statements like these are not helpful and do not do justice to the amount of work it takes to tune a car. It is not a simple procedure and to say that a dyno is used as a HP measurement tool only is misleading and not factual. A clear lack of understanding of the process even though it has been discussed at great length. The reason I spent almost 100K was not to tell you how much power your car does or doesn’t have.

 

I know that the power loss due to viscous resistance in oil is not linear, so that
in bearings that are shearing oil at 1500rpm or lower, the resistance is *much*
less than 2000rpm. For most typical-sized automotive bearings, there is a
pronounced jump in resistance at about 1500rpm (sorry not to have a
citation to refer. It was from a lubrication text).
Also, drivetrain loss depends on which gear (if this hasn't been said yet). Most
cars have gear boxes designed so their top gear (or maybe second from top)
is the most efficient (fewest shafts involved etc), for fuel efficiency and
longevity.
The frictional losses on the cylinder sidewalls during the power stroke are
the highest due to the combustion pressures, and are not reproduced when
the motor is being driven by the dyno during the rollback, so a rollback may
be a little optimistic.
The movement of air in the crank case due to the piston movement is
a factor, and air resistance increases at the third power of velocity (rpm).

 

Stephen,
I hope I didnt sound like "dynos are meaningless",
this is all good discussion!! What I was trying to say is;
Comparing Dyno figures from different websites (that are obviously
various cars on various dynos under various conditions) is pointless!!
The dyno figures from the last shootout (IN VEGAS) were very meaningful
to compare all of the cars to each other on that day. Regardless of what the
actual #s were. Now, to take those same numbers and compare them to
a different car on a different dyno, that is pointless. Now having said that,
I know that dynos are very useful in developing a variety of tuning scenarios,
IE, the ECU tuning. We also know that one little short run on a dyno does
not emulate real world situations like me driving my car hard around Brainerd
International speedway for 20 minutes of all out driving. The horsepower that
I am producing at the end of a hard session with full "heat soak" in effect is much
lower than the horsepower that I will have after a quick blast down the highway...
We are all seeing and understanding (hopefully) that there are alot of differences on how dynos are run, massaged and calculated.
"Let the buyer beware!" and keep your educated thoughts coming
Marty

 

RS Tuning do not have a chassis dyno. I believe Ruf ditched theirs and now use only their 2 engine dynos - The interesting thing is that (in the case of RS) they can tune a porsche tt so accurately on the engine dyno that it requires zero adjustment on the street. Happened with me and another RLer

Readers need to check out the credentials of the above two tuners when evaluating the validity of everything on this thread

IMO chassis dynos are for outfits which can't afford to pay the expense of buying and maintaining a top flight engine dyno. This is not necessarily the tuners fault in a market where their competitors are churning out high chassis dyno numbers for little $$$ where is the commercial sense in investing in a facility which uneducated customers would be unwilling pay for.

The tuners I know of in the US who go the engine dyno route in the US are:
Protomotive
Andial
Bob Holcomlbe
Are they cheap ????

 

It may be interesting to know that OEs can use two types of engine dyno for initial development , then road test,chassis dyno for final polish/issues.
Water brake engine dynos are superb for steady state mapping, retarder type engine dynos are much better for transient mapping.
This really is a big subject and I guess we should all be grateful that our cars drive so well after all this stuff !!!!!!!!!!!!!!!!!!
All the best

Geoff

 

Please enlighten us as to what you mean by this. I am sure we are all interested in what between the lines message you have here.
The funny thing is how many people here have any credentials in building, fabricating, tuning and production. I can count about 5 total on this board that fill that bill. The rest is all bench racing speculation.

Are you kidding me? Do you know what the cost is in comparison? It is a choice, not a financial issue. How can you make these statements and never even built an engine or tuned a car? I think these generalization are hilarious especially when it comes from a hearsay point of view or I saw it this way and every other way is wrong. It is amazing that the world is still flat and because you can't see the whole picture one assumes it is incorrect or doesn't exist. Do you assume that the cars I build drive like a model T because they were not done on a engine dyno? If so please provide actual data as to why. Can you lug my builds in fourth gear at 20MPH and pull out of them like a factory car. There are so many things here people don’t know they don’t know about actually tuning a car. I have to shake my head. Even when you do have it tuned is there any shred of understanding how to make it start in -20 degree weather or 120 degree weather and drive? I laugh at most of this. It is an endless loop of I saw, heard but never done. Sheez there are always several ways to do something. There is so much more to tuning car than most ever would or will understand.

 

I mean exactly what I have written - I tried to keep it dead simple. The worlds number 1 Porsche turbo race engine builder doesn't use a chassis dyno and another tuner who is well respected in the US just ditched his and only uses 2 engine dynos.
This is what the forums are about - you say your bit, others say theirs and readers/posters can research by looking up the above tuners and decide for themselves, and then make their minds up
You continually mock people for "not getting their hands dirty" and noone has ever challenged your ability to build a good motor - it is the mapping side and particularly the power measurement and sustainability which I continue to question - doing it on a chassis dyno is a band aid (albeit one which Manthey Racing and Gunther use )
I have no doubt from reading your various posts over the years that if you had a good engine dyno set up and the Autobahn and Nurburgring on your doorstep then you would be able to produce very similar products - the motivation behind the EVO range of products which you market seems to be the highest number on an 8 second dyno run with the smoothest possible torque curve.

Show me those 60-130s or better still 60-160s

 

And this is where I get upset. Why, because the practical experience of using either is not in your bag of tricks, yet your conviction is very strong it has to be one way. Have you talked to these companies and asked why they don’t use it? The factory does and has and did with their race programs as well. Then they finished it on the test track. I am not mocking the lack of experience, I am mocking the world is flat theory. Because it is not RS tuning the rest sucks? Have you driven what I build? Any of them? 996, 993, 930, 911? I build all sorts of stuff. Do you know what I really do? No. I gather not really. Do I build just motors, no. I keep quiet on most of the my car is faster threads. Why, I have nothing to prove. If I want to make a 1000HP and thought it was practical, I would build it. I do recall somewhere where a little 3.3 motor I built beat the crap out of an X50 making a hell of a lot more power than the lil 3.3.

See the problem here is while I help EVO and GIAC develop product you belittle and lump me with all. No offense but I have EFI converted 930s that would hand just about every one of these supertuned cars their ****. I don’t mention it though. Yet still you can drive it on the highway and get descent gas mileage and throw it in fourth gear at 20 MPH and smoothly pull it up to speed without bucking, hesitating or other. ME7.8 is a only a portion of the tuning I am involved in. The rest I hand write, build and fabricate and create reliable and ungodly fast 930s. I have been tuning EFI systems since the mid 90s. What is often touched on in these discussions is a 1/3 of what it takes and what really happens in the process.

So if I seem irritated, well I am. This crusade you continue on is sometimes laughable. I am very passionate about what I do. Remember, I am educated and have done a whole lot more than what I have chosen as a profession now. Since I sat on the side of dishing out cash and now sit on the side of building them I can practically relate the two and compare what is what. Buying and doing are two different things. I have said it before, I can show you pictures, tell you how to cook a turkey, even describe what it smells like when you wake up on thanksgiving day. And you truly would not get it until you experienced it for your self. You have an analytical mind. This has to make sense to you? I again will say it, I am not belittling your lack of experience, just the fact the nothing else is possible in your world other than the road by which the blinders show. I know as a father I try to teach my boys this is not the best path. Look, listen and learn.

I made a decision not to buy an engine dyno. Ask Kevin. He and I talked about this at great lengths. What I chose was based on my experience and need for a tuning tool. This doesn't make me a poor tuner. It means I arrive at the same result with a different tool. Again, you have not driven my product so you can not say this is not true.

What is funny, I am sitting on the dyno finishing up the tune on a 930 EFI right now. I wish I had the ring at more door step. Until then it is Heartland Park. As I have said before, when the weather clears I will give you your test.

 

Bloody hell you pushed that key so hard you sent it twive

Please..... do not get so irrate

I was reacting to you stating above that chassis dynos and the street are THE 2 MOST USEFUL TOOLS - by saying this you are effectively writing off the products offered by the 2 best Porsche tuners I know of - hence my post.

My "crusade" which you laugh at is alive and well - I am contemplating spending a good bit more serious $$$ (well actually it looks more like Euros ), and part of the process of convincing myself involves pouring over what other people are doing/claiming and frankly your 680RWHP grates .

Do you believe your 680RWHP would hold up at 7000rpm on the Autobahn in 35DegC heat 6th gear - WOT for 5 minutes - do you replicate this on your chassis rig ? If you can't, then how do you know what your temperatures are going to be after 5 minutes ? Do you care ?

Well unless you've got some pretty expensive air moving equipment, I doubt it - we are talking about different things here.

NOONE SAID YOU ARE A POOR TUNER

Why is it "belittling" to mention an 8 second dyno run - you of all people must realise how ridiculous it is to claim big hp numbers based on that. You have aligned yourself with that lot, so, despite your obvious other talents and credentials (with other Porsche and aftermarket EFI platforms) must realise that you are endorsing these methods.

Once again - Whilst crusading, I am not trying to be deliberatly deflamatory

 

Irritated, not irate. Beside, I cut my fingers off on my right hand years ago working on my 930. I can’t pound that hard That was an accident.

I was not imply this at all, I was stating that in reality, on the street the chassis dyno is a very valid tool and used correctly will provide a seamless product that will rival an engine tune. On the street with may variables you will not notice a difference. Caveat here is if done correctly.

If it makes you feel any better it is only 592 AWHP on my dyno.


“Do you think I would run that program at the Autobahn? Like any good engine builder I run different maps for different scenarios. I do know what my temps are at about 4 minutes 20 seconds under load while tuning. One of the things I do while tuning is watch charged temps, intake temps, oil temps. This is important while tuning or simply breaking a motor in. You can not leave this variable out. Aside from the fact I have 50K miles on my car something must be right since it is still in one piece. Would you agree? I am not driving Ms. Daisy.


Well if the dollar amount is any indication of the air moving equipment I have then I am probably ok. Rated for a constant CFM that will blow my 7 and 4 year off the dyno when standing in front of it. Not to mention the half dozen other fans we use to supplement the system. We didn’t just use ceiling fans here D I wish we could have. I have as much as a used Honda in air equipment. Have you not seen my main fan? It is 6 feet in diameter. It literally uses a propeller. This is just one of the many fans we use.

Because I have stated before that I do not do a 8 second run. Our runs are about 45 second pulls. I have my dynos I use with our product or someone else’s. If I want to play the marketing game I would have bought a dynojet and saved myself about 70K. I do not make it a habit of belittling other methods or companies. It simply does nothing for anyone. I worry about what I do and what I can provide. If this is guilty by association then I guess I am charged accordingly. But again you and I have had conversation how I tune and make my runs. I do 45 second runs and steady state which is far longer than 45 seconds btw. On Tues I ran this lil 3.4 for 4 hours straight. Yes, 4 hours. How much more stress can one provide than this?


So if I am not a poor tuner what might this mean. I am only sorta an idiot

Look, I just want you to understand that while you sit on the other side of the pond behind the keyboard and gather information, what we do and how we do it is not necessary wrong because others don’t agree. There is more than one way to do things and that doesn’t mean that the result would be different. It just means that it is different. I didn’t say that I was putting motors together with Duct tape and an AIC for fuel control and poor mans dynoing it. What we do and how we do it is not easy. What is often talked about on these board is about a 1/3 of what it takes and how we achieve what we do. Hell, I burn through more straps from headers glowing read from steadying then you can imagine.

It is all good in the end. I really didn’t mean to post that twice.

 

I suggest that anyone who is reading this thread go out and purchase a great book by Dave Walker.. Titled Engine Management.. Dave is a fellow Brit who has written some pretty good chapters in his book.. I wish that I could scan a few of his pages and post them.. But I will paraphrase a few ltems..

The biggest advantage of the dyno cell is that you are measuring torque directly from the crankshaft. You can also control the temperature, coolent temps and even air pressure. The biggest disadvantage is that the same engine is not operating under the same conditions as it will occur in the car. With a rolling road, the engine is running in exactly the conditions under it will operate in the car. The main disadvantage of the rolling road is that you are measuring the torque at the wheels, not straight off the engine.

Mr Walker will explain the differences between water brake and hydraulic engine dyno's and go into the differences between Eddy current/hydraulic brake wheel dyno's and inertia dyno's. There is more information about the difference between the two. However, a brake wheel dyno, vs a brake engine dyno can have equal outcomes.. One of my main decisions for purchasing a DynaPack was the ability to remove the wheel/tire issue and basically have a modified engine drivetrain dyno..

 

Kevin,
I know Dave Walker pretty well and yes, his book is good.
I dont think that the rolling roads as described in this thread do really replicate true road conditions.
Back in the UK, the F1 teams use moving floor wind tunnels to duplicate real conditions to check aerodynamics. 10,000 hp fans are used !!!!!!!!!!!!!!!!!!!!!!!!!
complete with power line sub stations. Mind blowing stuff ,where literally money is no problem
At even 80mph wind speed an adult can not stand upright!!

The big problem that has been mentioned by many is underhood temperatures and the inability of intercoolers to hold intake temperatures.
Its a battle I fought for years and I guess all operators can do when testing these big bhp motors is be careful and check temperatures frequently.

The big disadvantage of engine dynos is set up time , so in the end it all comes down to how the measuring system is going to be used and a big slice of personal preference !

All you dyno guys have at least one out here who understands the problems you face !!

Good luck

Geoff

 

Wow,

7000 Rpm in 6th ! Thats got to be around 210 Mph and for 5 minutes, i make that a 17.5 Mile straight clear road and one brave person.

Ive been on the autobahn a few times and let me tell you just achieving say 180 Mph for a few seconds is a challenge. On the one occassion i did hit 200 on the dash i had to pass a 60 Mph lorry at around 150 Mph then within a second i was up on traffic.

The up side is now i have the I/A stage 4 i get there alot quicker.

Please tell me where this autobahn is?